Can I capture screen contents in a picture?

Question

Hi,
I would like to know if I can capture contents of the screen (a UIImage and some Text) in single file and save the contents in the UserDefaults. The work around is to save the contents separately, but just wondering...
Thx - Sam.

Answer 1

Shnaps wrote:
I'd be curious about how the Cocoa can be 'nudged' to apply the pending changes.
Me too. As indicated in my last response, my understanding of this topic is fuzzy at best. A few months ago I was silly enough to describe my confusion in Software 101, and was rewarded with the following guidance from one of our experts:
The Cocoa event model is very thoroughly documented as are all the ways in which it may be bypassed for more immediate drawing tasks. There's no reason for any of this to be even remotely mysterious unless you simply haven't read any of it.
The author of the above is known for developing newbie abuse into an art form and I often begin my day by reading from the collection of his works I've managed to save over the past year. Some of these are quite rare btw, since they were deleted by management within a few minutes of publication.
I've yet to discover the documentation referred to above, or if I have, I didn't understand a word of it. If you're interested in general background, a good starting place might be The Event-Drawing Cycle, Revisited in the +Cocoa Fundamentals Guide+.
For the synchronization problem at hand, I think my first try would be one of the performSelector methods of NSObject.
I'm fairly sure it would be easy to hide the controls, then start the screen capture in a subsequent event cycle using performSelector:withObject:afterDelay:. However, the doc advises:
Specifying a delay of 0 does not necessarily cause the selector to be performed immediately. The selector is still queued on the thread’s run loop and performed as soon as possible.
Without testing I have no idea whether "asap" precludes the possibility of flicker.
Another method to look at is performSelectorOnMainThread:withObject:waitUntilDone:. I think this would set the hidden property immediately, as advertised. But I don't know whether the immediate processing would include updating the view.
If none of the performSelector methods do what you want, and you continue to have interest in this topic, it might be a good idea to start a new thread on how to ask Cocoa for a view update in the middle of an event cycle (or maybe how to ask for execution in a desired order?).
\- Ray